Computers can be used to present information in the form of images on a display device. An image, which the user can visualize, includes graphics, characters, words, and text as well as other display features such as colors. A display device that can display graphical output is called a graphical user interface ("GUI").
A GUI is a type of computer interface which allows accessing actual objects that a user can access and manipulate. The GUI provides a visual aid to assist the user to enter values as well as entering the various objects and attributes to create a graphical representation.
One type of graphical representation that is difficult to visualize is that of a three-dimensional space on a two-dimensional display device. The creation of three-dimensional space on a two-dimensional display device is known as 3D rendering. Resource intensive calculations are often necessary in order to render three dimensional space from a particular point of view. The calculations are more resource intensive with respect to viewing trajectories of celestial bodies and spacecraft (e.g., satellites) in three-dimensions. This is at least in part due to the complexity of the trajectories of the celestial bodies and spacecraft that is caused by the nature of multi-body interaction therebetween. Currently, personal computers usually cannot be utilized to view 3D graphic representation of space trajactories because a graphical user interface does not exist whereby a user is able to view and edit a spacecraft's trajectory in three-dimensions.
The inventors of the present invention recognized a need to create a tool that allows current GUIs to enable a user to visualize a spacecraft's trajectory as well as allow the user to edit and select the data they wish to view. Furthermore, the inventors recognized a need for real time rendering in determining the position and velocity of celestial bodies with respect to one another at some finite time interval. That is, they recognized a need for a tool which can calculate the trajectories of various objects, i.e., planets, satellites, spacecrafts, comets, asteroids, at a particular time interval.
Many exploratory spacecraft travel to various planets in our solar system. Most persons conceptualize the orbit line of the spacecraft as launched from Earth and traveling to the target destination in a straight line path. In actuality, a spacecraft orbits in the planet's gravitational pull around the Sun. The orbit of each planet is approximately an ellipse with the Sun as one of the focus points. A spacecraft usually escapes from a planet's gravitational pull by following a trajectory that is substantially parabolic. In this way, a spacecraft launched from the Earth travels in orbit around the Earth and then coasts either further from or closer to the Sun, depending upon its destination, until it crosses the orbit of the next planet. Therefore, the spacecraft's trajectory would appear substantially parabolic where the beginning point is where the spacecraft is launched from and the ending point is the final destination of the spacecraft.
For example, if a spacecraft was to travel from Earth to Jupiter, the spacecraft would not travel directly in a straight line between the two planets. Instead, the spacecraft is usually launched in the same direction that the Earth moves around the Sun. The spacecraft coasts outward from the Sun until it crosses an orbit into Mars and continues to orbit Mars until it escapes into Jupiter's orbit.
The inventors recognized that this path is completely counter-intuitive. The inventors recognized that what is needed, therefore, is a system and method for object selection and trajectory modification which provides visually intuitive and directly manipulable ways of editing the spacecraft's trajectory, on a GUI, in the context of real time.
The inventors of the present invention recognized a need for a tool that allows the GUI to display objects in three-dimensions, and draw each celestial body or satellite in its current location in space. This tool may be used for educating the general public on their perception of the spacecraft's trajectory. In accordance with the invention, a preferred GUI displays the relationship of each celestial body with respect to another body. A user may select to and from where they wish to view the three-dimensional trajectory for the objects whose ephemeris files are calculated. In addition, the user may flexibly and conveniently display and edit the trajectory to any date and time the user wishes to view.
The present embodiment generates a three-dimensional graphical representation of the environment, i.e., the user's perspective of a graphical universe including items such as a satellite's trajectory. Furthermore, the present invention displays trajectories of various objects in three-dimensions while permitting the user to edit the features by directly manipulating the data.
Accordingly, the inventors recognized a need in three-dimensional processing for real time three-dimensional rendering which allows a user to move the three-dimensional space in real time along any axis of a reference frame and which can further allow the user to view a satellite's trajectory on a personal computer system.
It is therefore an object of the present invention to provide an improved computerized method and apparatus for representing a three-dimensional view of space with celestial bodies and spacecrafts.
It is another object of the present invention to provide an improved method and apparatus for rendering a three-dimensional space on a two dimensional graphics display in real time.
It is yet another object of the present invention to allow a user to efficiently translate and rotate the viewing position along any axis.
It is yet another object of the present invention to visualize a three-dimensional representation of a spacecraft's trajectory.
It is yet another object of the present invention to provide an interactive computer system which allows a user to move the celestial bodies and spacecrafts forwards and backwards in time.
The present invention addresses these needs by a trajectory visualization tool that enables a user from a computer including a personal computer, to view a three-dimensional representation of a spacecraft's trajectory and the trajectories of any planets or spacecrafts of interest. The tool reads in two ephemeris files which include tables of the computed positions of celestial bodies and spacecrafts. One of these files is for the spacecraft and one is for the planets. The tool uses these to calculate the Cartesian coordinates of the objects and their trajectories. This information is then plotted and displayed on the GUI. Using a pointing device (e.g., a mouse), the user can manipulate a slider on the GUI to move the spacecraft and planets forward or backward in time to their relative positions at any point within the time span of the ephemeris file. This allows the user to visualize trajectory information.
This tool allows a user who is unfamiliar with celestial mechanics to grasp the details, complexities, and constraints of a spacecraft's trajectory.
Accordingly, there is provided an interactive computer system that reduces the time and skill-level to project a trajectory visualization tool that presents a three-dimensional picture of a spacecraft's trajectory and provides vital orbital information.
A preferred computer system for processing data of a spacecraft's trajectory comprises: first memory means for storing positioning and timing information of said spacecraft and a plurality of celestial bodies including the Earth and Sun; first data processing means for calculating ephemeris data of said spacecraft and said celestial bodies; an user interface for entering user option data on said spacecraft's trajectory, said user option data comprising launching location and time and landing location and time of said spacecraft; graphic processing means for rendering graphic representation of said ephemeris data of said spacecraft and said celestial bodies, said graphic rendition being dictated by said user option data; and a graphic display for displaying said spacecraft's trajectory.